HP & Track Time Guesstimate???

Gearhead999 · 02-05-2006, 11:16 AM

Not to get into a flame war here.
You are right that the intake valve is opened when the piston is on its downstroke [intake stroke] and there interferance isn't a problem.

But, the intake valve, many times, on performance cams opens before top dead center [BTDC] and closes after bottom dead center [AFDC]. I pasted part of a cam spec card for a Crane Hyd Roller HR-216-325-2S-12.

You can see that the Intake valve opens at 28.0 degrees BTDC and closes at 70.0 degrees ABDC. That is why I would be concerned about valve to piston clearance at TDC. And the Exhaust valve opens 76.0 before bottome dead center [BBDC] and closes at 30.0 degrees after top dead center [ATDC]. So the valves are open at TDC, where clearance becomes an issue.

Lift: Intake @Cam 325 @Valve 520 All Lifts are based
on zero lash and theoretical rocker arm ratios.
Exhaust @ Cam 339 @Valve 542
Rocker Arm Ratio 1.60

Cam Timing: TAPPET @.004
Lift: Opens Closes ADV Duration
Intake 28.0 BTDC 70.0 ABDC 278.0 °
Exhaust 76.0 BBDC 30.0 ATDC 286.0 °

Take care, Go STEELERS !!!!

Dark_5.0 · 02-06-2006, 02:23 PM

Quote:

Originally Posted by Gearhead999

Not to get into a flame war here.
You are right that the intake valve is opened when the piston is on its downstroke [intake stroke] and there interferance isn't a problem.

But, the intake valve, many times, on performance cams opens before top dead center [BTDC] and closes after bottom dead center [AFDC]. I pasted part of a cam spec card for a Crane Hyd Roller HR-216-325-2S-12.

You can see that the Intake valve opens at 28.0 degrees BTDC and closes at 70.0 degrees ABDC. That is why I would be concerned about valve to piston clearance at TDC. And the Exhaust valve opens 76.0 before bottome dead center [BBDC] and closes at 30.0 degrees after top dead center [ATDC]. So the valves are open at TDC, where clearance becomes an issue.

Lift: Intake @Cam 325 @Valve 520 All Lifts are based
on zero lash and theoretical rocker arm ratios.
Exhaust @ Cam 339 @Valve 542
Rocker Arm Ratio 1.60

Cam Timing: TAPPET @.004
Lift: Opens Closes ADV Duration
Intake 28.0 BTDC 70.0 ABDC 278.0 °
Exhaust 76.0 BBDC 30.0 ATDC 286.0 °

Take care, Go STEELERS !!!!

They go hand in hand you can get away with a lot of lift if you limit the duration and you can get away with alot of duration if you limit the lift.

Go Referee's

88workcar · 02-20-2006, 08:27 AM

Bow tie eater. Diff subject. Your profile says best 60ft 2.1, work on this first. You will be shocked at your 1/4 times when you start knocking down some 1.6 60fters. A good holeshot has whooped many-a-man.

BowTie Eater 5 Liter · 02-20-2006, 08:44 AM

workcar, the 2.1 was like 4 years ago with my first mustang, ive been working on the launch big time, but going to invest in some slicks or dr's

02-05-2006, 11:16 AM	#1
Gearhead999 Registered Member Join Date: Sep 1998 Location: Oviedo, FL Posts: 992	Re: HP & Track Time Guesstimate??? Not to get into a flame war here. You are right that the intake valve is opened when the piston is on its downstroke [intake stroke] and there interferance isn't a problem. But, the intake valve, many times, on performance cams opens before top dead center [BTDC] and closes after bottom dead center [AFDC]. I pasted part of a cam spec card for a Crane Hyd Roller HR-216-325-2S-12. You can see that the Intake valve opens at 28.0 degrees BTDC and closes at 70.0 degrees ABDC. That is why I would be concerned about valve to piston clearance at TDC. And the Exhaust valve opens 76.0 before bottome dead center [BBDC] and closes at 30.0 degrees after top dead center [ATDC]. So the valves are open at TDC, where clearance becomes an issue. Lift: Intake @Cam 325 @Valve 520 All Lifts are based on zero lash and theoretical rocker arm ratios. Exhaust @ Cam 339 @Valve 542 Rocker Arm Ratio 1.60 Cam Timing: TAPPET @.004 Lift: Opens Closes ADV Duration Intake 28.0 BTDC 70.0 ABDC 278.0 ° Exhaust 76.0 BBDC 30.0 ATDC 286.0 ° Take care, Go STEELERS !!!! __________________ "Support our Troops" Dave 1968 Cougar 2004 Thunderbird 2007 F150 Harley-Davidson, SuperCrew 1986 LTD 1997 Ranger 1992 Honda Civic

02-20-2006, 08:27 AM	#3
88workcar Registered Member Join Date: Oct 1999 Location: Pierre Part, La. U.S.A. Posts: 1,850	Re: HP & Track Time Guesstimate??? Bow tie eater. Diff subject. Your profile says best 60ft 2.1, work on this first. You will be shocked at your 1/4 times when you start knocking down some 1.6 60fters. A good holeshot has whooped many-a-man. __________________ 88workcar 1988 Mustang LX 342. 417rwhp @ 6800. 28 X 10 ET Drag, 4.30s, 10.69 @ 126.43 1.42 60ft. 11.13 @ 127.7 on BFGs 1.72 60ft Rice Hater # 42 To be old and wise, You must first be young and stupid I'm somewhere in tthe middle.

02-20-2006, 08:44 AM	#4
BowTie Eater 5 Liter Registered Member Join Date: Nov 2000 Location: Maple Ridge B.C. Canada, The Best Place In The World Posts: 871	Re: HP & Track Time Guesstimate??? workcar, the 2.1 was like 4 years ago with my first mustang, ive been working on the launch big time, but going to invest in some slicks or dr's __________________ 1984 Bronco II, 36" Michelin Military Tires, 95 EFI 5.0, NP435 Tranny, NP208 Doubler, NP205 Transfer Case, Fill Size Solid Dana 44 Front End, WH Progressive Rate Rock Crawling Coils, Bronco 8.8 Rear, Skyjacker Softride Leafs, 5.13 Gears, Detroit Locker. Final Crawl Ratio Of 175:1 88 GT Best 60ft. 2.181 Best ET 14.350 Best MPH 98.01 ~WRECKED!!!!~

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